1. Field of the Invention
The present invention relates to methods of manufacturing GaN monocrystalline substrates used in light-emitting devices, such as light-emitting diodes (LEDs) and laser diodes (LDs), made from Group III-V semiconductor compounds.
2. Description of the Background Art
As a way of manufacturing large-scale, low-dislocation-density GaN-crystal thick films for application as substrates in LEDs, LDs and other light-emitting devices made from Group III-V semiconductor compounds, one method that has been proposed is, when growing GaN crystal onto a base substrate using a vapor growth technique, to form in the crystal-growth surface pits that define facet planes and to confine the dislocations to, or quench the dislocations along, the boundary lines of the facet planes of the pits, to grow GaN substrates of large area and slight dislocation density. (Cf. Japanese Unexamined Pat. App. Pub. No. 2001-102307, for example.)
A problem with this pit-employing method of manufacturing GaN crystal substrates, however, has been that along with the GaN crystal growth the pits grow too, enlarging diametrically, which lessens the effective GaN crystal portion that can be obtained by separating off the grown GaN crystal in thin, platelike form.